Caliper



April 6, 1943. D. MCGREEVY 2,315,806 u CALIPER Filed Aug. 2, 1941 Patented Apr. 6, 1943 U Nl TE? STAT- .5S E li 'i i? FiC E CALIPER Dennis McGreevy, New Orleans, La. Application August 2, 1941, Serial No. 405,251

1 Claim.

This invention relates to calipers and more particularly to a special construction of caliper adapted to indicate on a greatly enlarged scale slight variations in diameter of the object rneasured.

An object of the present invention is to provide an improved caliper having a simplified system of levers by means of which very slight variations will be greatly magnified and indicated on a greatly enlarged scale.

Other objects will more particularly appear in' the course of the following more detailed description.

The invention consists in the novel construction, arrangement and combination of parts hereinafter more particularly described and claimed.

lOne sheet of drawings accompanies this specication as part thereof in which like reference characters indicate like parts throughout.

Figure l is a plan view of an improved caliper;

Figure 2 is a fragmentary side View of Figure 1;

Figure 3 is a fragmentary cross section taken on line 3 3 of Figure 1;

Figure 4 is a fragmentary longitudinal cross section through the contact feeler carriage on line 4-4 of Figure l;

Figure 5 is a fragmentary cross section through lever I'l at its pivot end;

Figure 6 is a fragmentary cross section on line S--B of Figure 5;

Figure 7 is a fragmentary plan View of the invention applied to internal calipers; and

Figure 8 is a fragmentary side elevation of Figure 7.

According to the embodiment of the invention illustrated in the accompanying drawing the calipers comprise two legs I-I, pivoted at one end as at 2 and having their short arms notched at 3 to receive a spring ring d. The long arms of the legs are provided with pivoted stud posts 6 and 1 and a threaded rod 5 is pivoted at one end to pivot post 6 and passes freely through an orifice in pivot post 'I carrying on its outer end a knurled thumb nut 8 by means of which the legs can be adjusted under the presssure of spring 4. The structure thus far described is standard and well known caliper practice.

In the case of external calipers er calipers intended to measure the outside diameters of objects, one of the legs I is as usual provided with an inwardly facing contact end I9 while in accordance with the present invention the long arm of the opposite leg I has its outer end part bent to conform substantially with a tangent to an arc struck from the pivot 2 of the calipers. This tangential portion I5 of the leg I is preferably formed by bending the leg I outwardly as at I2 and then inwardly as at i3. On the portion I5 is xedly mounted a carriage 23 herein illustrated as having a slot on its lower face adapteed to embrace the portion I5 of leg I, and secured thereto by pins 25-25. The carriage 23 is further provided with a longitudinally extending bore 2l parallel with the portion I5 of leg I, and in this bore 2l is slidably positioned a feeler pin 2B, the ends of which project from either end of the carriage 23. Preferably the outer projecting end of feeler 28 is somewhat enlarged as at 23 by. means of which its motion inwardly is limited. A lever is pivoted on the portion I5 of leg I as by screw 22, and its upper short arm 20 is provided with a laterally directed pin 2| extending behind and adapted to engage the enlarged end 29 of feeler 28. The long arm I9 of this lever projects downwardly to engage the short arm I8 of a second lever pivoted to leg I adjacent the bend I2 as by screw I6 and the long arm I'I of this lever is formed as a pointer and arranged to play over the side face of carriage 23 which latter is provided with spaced indicia 26.

Tensioning means is provided and arranged to rotate lever Il in a counter-clockwise direction so that feeler 23 is normally projected toward the opposite contact point Ii). This tensioning means is provided by means of a thirnble comprising a head with concentric spaced flanges 4I and 42. The outer flange seats in an orice 43 in lever Il. The screw I3 passes within the inner flange 42 and is threaded into caliper leg I. A coil spring i4 is positioned between the ilanges having one end engaged on a pin 45 the ends of which seat respectively in leg I and the head of thimble lill. The other end 4t of spring i4 extends through a slot 4l in the outer flange and engages the lever I8 within a recess 48.

In the case of internal calipers or calipers adapted to measure interior surfaces the device is similarly arranged but the caliper legs I'-I having one Contact end pointed outwardly has the feeler carriage 3l reversely positioned so that the feeler 23 also points outwardly, and its enlarged inner end 36 is engaged by the pin 35 carried by the short arm 34 of a lever pivoted on a portion 32 of leg I' arranged tangentially to an arc struck again from the pivot of the caliper legs. In this embodiment the pointer lever 33 is pivoted at one end as by screw 3i, which is associated with a tensioning device similar to that previously described, and the long arm 33 of le- Vthe pivot of ver 34 engages pointer lever 33 adjacent its pivot.

In both embodiments of the invention it will be apparent that the feeler pin 23 is slidable on its long axis in a line substantially tangential to the caliper legs and in alignment With the oppositely disposed contact end of the opposite leg. Very minute movements of the feeler pin 28 are reected by the: two levers on a greatly enlarged scale so as to be easily read by the operator.

Various modiiications in the precise construction and arrangement of parts will readily suggest themselves to those skilled in the art but Within the scope of the present invention as claimed.

Having thus fully described my invention I claim:

In a caliper having pivoted legs with a slidable contact finger mounted on the end of one leg and a lever mounted on that leg arranged to operate the slidable contact finger, an indicator finger in operative contact with said lever having a pivotal orice formed with a radially disposed notch, a thimble formed with concentric spaced annular flanges, the outer flange of the thimble forming a bearing seat for the pivotal orifice of the nger, means extending through the inner annular flange to secure the thimble to the caliper leg, a coil spring positioned intermediate the anges with one end engaged in the radial notch of the iinger, and an anchoring post positioned to engage the other end of the spring, the thimble and the caliper leg.

DENNIS MCGREEVY. 

